Recently just upgraded to SQL Server 2008 R2 Express. When I attempt to create a database after logging in using Windows Authentication with my id myuser I receive this erro
I have 2 accounts on my windows machine and I was experiencing this problem with one of them. I did not want to use the sa
account, I wanted to use Windows login. It was not immediately obvious to me that I needed to simply sign into the other account that I used to install SQL Server, and add the permissions for the new account from there
(SSMS > Security > Logins > Add a login there)
Easy way to get the full domain name you need to add there open cmd echo each one.
echo %userdomain%\%username%
Add a login for that user and give it all the permissons for master db and other databases you want. When I say "all permissions" make sure NOT to check of any of the "deny" permissions since that will do the opposite.
You may be an administrator on the workstation, but that means nothing to SQL Server. Your login has to be a member of the sysadmin role in order to perform the actions in question. By default, the local administrators group is no longer added to the sysadmin role in SQL 2008 R2. You'll need to login with something else (sa for example) in order to grant yourself the permissions.
In SSMS 2012, you'll have to use:
To enable single-user mode, in SQL instance properties, DO NOT go to "Advance" tag, there is already a "Startup Parameters" tag.
Coming late to the party, but I found this fantastic step-by-step guide on getting control of your SQLExpress instance if you don't have your sa password. I used this process to not only reset my sa password, but I also added my domain account to all the available server roles. I can now create databases, alter logins, do bulk operations, backups/restores, etc using my normal login.
To summarize, you use SQL Server Configuration Manager to put your instance into single-user mode. This elevates you to sysadmin when you connect, allowing you the ability to set everything up.
Edit: I've copied the steps below - kudos to the original author of the link above.
I followed the steps in killthrush's answer and to my surprise it did not work. Logging in as sa I could see my Windows domain user and had made them a sysadmin, but when I tried logging in with Windows auth I couldn't see my login under logins, couldn't create databases, etc. Then it hit me. That login was probably tied to another domain account with the same name (with some sort of internal/hidden ID that wasn't right). I had left this organization a while back and then came back months later. Instead of re-activating my old account (which they might have deleted) they created a new account with the same domain\username and a new internal ID. Using sa I deleted my old login, re-added it with the same name and added sysadmin. I logged back in with Windows Auth and everything looks as it should. I can now see my logins (and others) and can do whatever I need to do as a sysadmin using my Windows auth login.